The present invention relates to a machine for removing material and more particularly to a milling machine for cutting curved or spherical plate to size and preparing its edges prior to welding.
An example of where a large amount of plate cutting to size and edge preparation prior to welding must be done is in the fabrication of spherical tanks for the containment of liquidified natural gas (LNG). Thus, in the article entitled "Aluminum and LNG -- New Perspective on a Changing Partnership" by George E. Herrman and Donald E. Branscome, PIPELINE & GAS JOURNAL, June 1973, there is shown in FIG. 9 a spherical tank constructed by welding together a plurality of spherically curved, "orange-peel" sections. These orange-peel sections are first cut to size and the edges prepared, this being followed by the welding together of the plates into the final spherical tank.
Background on the edge preparation of plate prior to welding can be obtained, for example, from the article entitled "Joint Design and Edge Preparation", which occurs on page 297 of Volume 6 (Welding and Brazing) of the METALS HANDBOOK, 8th Edition, American Society for Metals, 1971. Thus, in the welding of aluminum plate, it may be advantageous to use the double-V-groove butt joint pictured on page 298 of the referenced Volume 6. The plate edge preparation suitable for making a double-V-groove butt joint can be performed by moving an appropriately formed, milling machine cutting tool by the plate edges. Furthermore, if the milling machine cutting tool is moved on a particular path relative to the curved plate, the plate will be cut to the correct size while simultaneously preparing the edge for welding.